<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css" class="css">
			/*
				n 边形的外交和为 360 
				单个外角 360/n
				n 边形的内角 180 - 360/n
			*/
			*{
				margin: 0px;
				padding: 0px;
			}
			.wrap{
				position: absolute;
				top: 0px;
				right: 0px;
				bottom: 0px;
				left: 0px;
				margin: auto;
				
				width: 300px;
				height: 300px;
				border: 1px solid;
				
				perspective: 200px;
				/* transform-style: preserve-3d; */
			}
			.wrap > .box{
				position: absolute;
				top: 0px;
				right: 0px;
				bottom: 0px;
				left: 0px;
				margin: auto;
				
				width: 100px;
				height: 100px;
				transition: 1s;
				transform-origin: center center -28.8675px;
				transform-style: preserve-3d;
			}
			.wrap > .box > div{
				position: absolute;
				
				width: 100px;
				height: 100px;
				background-color: pink;
				text-align: center;
				font: 30px/100px "微软雅黑";
				backface-visibility: hidden;
				transform-origin: center center -28.8675px;
			}
			.wrap > .box > div:nth-child(1){
				/* transform: rotateY(0deg); */
			}
			.wrap > .box > div:nth-child(2){
				transform: rotateY(120deg);
			}
			.wrap > .box > div:nth-child(3){
				transform: rotateY(240deg);
			}
			.wrap:hover .box{
				transform: rotateY(360deg);
			}
		</style>
	</head>
	<body>
		<div class="wrap">
			<div class="box">
				<div>1</div>
				<div>2</div>
				<div>3</div>
			</div>
		</div>
	</body>
</html>
